She has to pay $503.125 monthly till 4 years
Explanation:
Cost of the ring = $30000
Add on = 5.5% of the cost of the ring
=( 5.5 x 30000) /100
= $1650
Down payment = 25% of the cost
= (25 x 30000) /100
= $7500
Time = 4 years
Loan amount = 30000 - 7500
=$ 22500
Total amount to pay = 22500 + 1650
= $24150
Monthly instalment= 24150/(4 x 12)
= $503.125
She has to pay $503.125 per month till 4 years.